Chain link pipe wrench with plural handle-saw surfaces



y 19-60 R. w ves: 2,944,452

CHAIN LINK PIPE WRENCH WITH PLURAL HANDLE-JAW SURFACES Filed April 10. 1959 INVENTOR ROBERT W- V05! ATTORNEYS pipe.

f 2,944,452 ,7 up CHAINLINK PIPE WRENCH WITHPLURAL HANDLE-SAW SURFACES Robert W. Vose, West Springfield, Mass assignor to Moore Drop Forging Company, Springfield, Mass, at

' corporation of Massachusetts Filed Apr. 10, 1959, Ser. No. 805,593

,3 Claims. 'j c1. sic-6s invention relates to pipe wrenches, and particularly to reversible pipe wrenches of the type having a binding chain. I he principalobject of this invention is to providean improved pipe wrench ofjthe. above type having constructional characteristics enabling it to be used on pipes of a wide range of sizes with generally uniform gripping action and without any tendency toicrush the It is another object of this invention to provide animprovedp pe wrench of the above type of compact size enabllng it to be used in confined spaces.

It is a further object of this invention to provide an '7 improved ,pipe .-wrench of simplified construction facilitating its manufacture and enhancing its appearance.

The above and other objects and advantages of this invention will be apparentfrom the following description V Fig. 4 is a diagrammaticahshowing of the bending stresses on a portion of the wrench undera given load condition; and a Fig. 5 is a diagrammatical showing themanner in which the curvatures of the toothed gripping surfaces are obtained.

Referring in detail to the drawing, a wrench 8 is shown embodying this invention. The wrench is of integral construction and includes a handle portion 10 of generally uniform cross section and a head portion '12 "which extends forwardly and is angled upwardly from the handle.

The undersurface of the head 12 includes convexly curved gripping surfaces 14 and 16 having oppositely extending teeth for selective forward and reverse rotation of pipe sections such as indicated at 18. Av flat link chain 20 is anchored to the shank portion of the wrench by a riveted pin 22 which extends through a hole 23. The chain includes pins 24 which extend laterally outward of the chain. The pins 24 are releasably eng'ageable by hook portions 26 at the outer end of the head .12 to hold the chain about thepipe v18. The chain 20 clamps or binds the pipe 18 to either one or the other of the toothed surfaces 14 or 16, depending 'on the direction in which the pipe is to be rotated. In Fig. 1 the tooth gripping surface 16 is engaged with the pipe 18 for rotation of the pipe in a counterclockwise direction. In Fig. 3 the gripping surface '14 is engaged with the pipe for rotation in a clockwise direction. A recess 17 is provided between the gripping surfaces aifording suflicient clearance to permit the transfer of a pipe from one gripping surface to another without releasing the chain. This 2,944,452 Patented July 12, 1969 The pin '22 by which the chain 20 is anchored to the wrench is located at a point closely adjacent the neutral axis 27 (Fig. 4) of the wrench. Since bending stresses are minimum near the neutral axis of a lever, as illustrated by stress vectors 29 in vFig. 4, thelocation of the hole 23 closely adjacent the neutral axis 27 has minimal weakening effect on the wrench. It has been thus found unnecessary to provide oifsets, webs and other strengthening elements which increase the bulk ,of the. wrench.-

A pair of flat links 28 are pivotably mounted on -the pin 22 on opposite sides of the wrench. The links extend below the undersurface of thewrench andthe ichain 20 extends from the lower ends of the links 28. The free end of the chain. is engageable by the hooks'26.dis-- posed at the forward end of the wrench head. Thehead 12 is of only slightly greater thickness than the wrench handle 10 enabling the wrench to be used in confined spaces, on short nipples, narrow flanges and the like. Shoulders 30. are disposed forwardly. of the pin '22 and engageable bythe links 28 limiting the pivotal movement of the links. The toothed surface Hex-tends rearwardly of the shoulders 30. Thisprovides relatively long effective pipe gripping surface without consequent increase in the size ofthe wrench head. 7

The outer end of the head His of a.bifurcated construction defining a slot 32 adapted to receive portions of the chain link engaged by. the hooks 26. Portions of the toothed surface 16 extend beyond the inner end of slot 32. This provides a relatively long gripping surface .of the user facilitating the engagement and ratchetingof the chain by the hooks. The head construction, including the relatively long gripping surfaces 14 and 16-which extend beyond the shoulders 30 and the slot 32, enables recess also permits the chain to be released from/the a pipe.

with a relatively small span of the chain required to bind a. pipe against saidsurfaces. 4.0

The curvatures of the tooth gnppmg surfaces 14 and 16 are defined by spirals 34 and 36 shown in Fig. 5. These spirals are of the logarithmic or equiangular type defined by the polar equation r=ae 9 in which m=arc cotangent of v, v is equal to an angle between 60-75, v being defined as the angle the spiral makes with its generating radii, a=r when 0=0, 0 is the polar angle of any point on the spiral, and e is the base of Napierian logarithms. The spirals are symmetrical, having a common point of origin 38'which is located on a straight line 40 of a length a from the anchorage pin 22 to the hooks 26. The origin 38 is located a distance b from the anchor pin 22; b equals a, the distance from the'pin to the hooks 26. The location of the origin 38 and the value of the spiral angle v have been empirically determined to insure generally uniform wrench gripping action for a wide range of pipe sizes. found that spirals having an angle v greater than result in gripping surfaces which tend to skid or slip on This is particularly so if the teeth are somewhat dulled or if the pipe is of relatively hard material. having angles v less than 60 have been found too shallow and the gripping surfaces have a tendency to crush pipes under the binding force of the chain 20.

This wrench may be conveniently made of an integral steel forging with carburized and hardened teeth. The wrench is relatively light weight consistent with the required strength and has minimum bulk enabling it to be used in cramped quarters. In addition, there is easy accessibility for chain adjustment and adaptability to a wide range of pipe sizes.

Having thus described this invention, what is claimed is: 1. A chain pipe wrench comprising a handleportion,

For example, it was.

Spirals a head portion extending forwardly of said handle, toothed gripping surfaces of convex curvatures on the undersurface of said head portion for selectively rotating a pipe in forward and reverse directions, a binding chain pivotably anchored on saidwrencln'said head including means for releasably engaging the free end portion of the chain to bind said chain about a pipe and against one of said gripping surfaces, the curvatures of said gripping surfaces being defined by symmetrical equiangular spirals having a common point of origin located on a straight line extending from the anchorage point of said chain to chain engaging means and 2 the distance from said anchor point to said chain engaging means, each of said spirals forming an angle of between 60 and 75 degrees with its generating radii. I

2. A chain pipe wrench comprising a handle portion of generally uniform cross section, a head portion extending forwardly and upwardly of said handle, first and second gripping surfaces of convex curvature on the undersurface of said head extending from the inner to the outer end of said head, said surfaces having oppositely extending teeth, a pipe receiving recess intermediate said gripping surfaces, a binding chain anchoredon the shank portion of said wrench adjacent the neutral axis of said handle, said chain including a plurality of outwardly extending pins, the anchored portion of said chain being in the form of a pair of links pivotably mounted on opposite sides of said Wrench and extending below the undersurface thereof, said head including shoulder portions engageable by said links to limit their extent of pivotal movement, spaced hooks disposed on the forward upper end portion of said head for releasably engaging the pins on the free end portion of said chain to hold said chain in binding relation about a pipe, and a chain receiving slot in-the outer end of said head extending from the top to the bottom thereof, portions of said toothed gripping surfaces extending beyond the inner end of said slot and said shoulder portions, the convex curvature of said gripping surfaces'being defined by symmetrical equiangular spirals having a common point of origin located on a straight line extending from the chain anchorage point to said chain'eng'aging hooks and the distance from said anchor point to said hooks, each of said spirals forming an angle of between 60 and 75 degrees with its generating radii.

3. A chain pipe wrench comprising a handle portion,

a head portion extending forwardly and upwardly of said.

handle, toothed gripping surfaces of convex curvature on the undersurface of said head extending from the inner to the outer end of said head, including oppositely extending teeth for selectively rotating a pipe in forward and reverse directions, a binding chain anchored on the shank portion of said wrench adjacent the neutral axis of said handle, said chain including a plurality of outwardly extending pins, the anchored portion of said chain being in the form of a pair of links pivotably mounted on opposite sides of said wrench and extending below the undersurface thereof said head including shoulder portions engageable by said links to limit their extent of pivotal movement, spaced hooks disposed on the forward end portion of said head for releasably engaging the pins on the free end portion of said chain, and a chain receiving slot in the outer end of said head extending from the top to the bottom thereof, portions of-said toothed gripping surfaces extending beyond the inner end of said slotand said shoulder portions, the convex curvature of said gripping surfaces being defined by symmetrical equiangular spirals having'a commonpoint of origin located on a straight line extending from the chain anchorage point to said chain engaging hooks and intermediate said anchor point and hooks, each of said spirals forming an angle of between 60 and 75 degrees with its generating radii.

References Cited in the file of this i patent UNITED STATES PATENTS 354,197 Leib Dec. 14, 1886 514,721 Mahnicke "Feb. 13, 1894 968,335 Farrell Aug. 23, 1-910 1,410,993 Carll Mar. 28, 1922 1,470,161 Gray Oct. 9,1923 2,726,564- Petersen Dec. 13, 1955 FOREIGN PATENTS 15,647 Great Britain 1906 

